1. Field of the Invention
This invention relates to a remote-controllable automatic telephone answering device.
2. Description of the Prior Art
It is well-known that the so-called remote-controllable automatic telephone answering device of the known type has a function for automatically responding to a ringing signal (16 Hz) sent from a calling party over a communication circuit to maintain the communication circuit in the communication loop state for sending out an answering message previously recorded on an answering message recording tape to the calling party, and a function for automatically recording a calling party's message on a calling party's message recording tape (hereinafter called as a message recording tape) and, in addition, a function for rewinding and reproducing the message recording tape in response to a specific remote control signal sent from a remote place over a communication circuit, thereby to enable listening to the calling party's message at the remote place.
There have been proposed various systems for receiving a remote control signal in such a device. In any of the conventional devices of this kind, there has been adopted a system which once sends out an answering message to the calling party to inform him of recording his message and then switches the device to the message recording state and receives a remote control signal in the message recording state.
In other words, the conventional remote-controlled automatic telephone answering devices employ a method which receives the remote control signal from the calling party in the abovesaid message recording state and records the remote control signal itself or a mark signal from an internal oscillator for a certain period of time and then rewinds the recording tape for a predetermined period of time or to the starting end of the tape.
In such a method, when an ordinary calling party other than the remote controller records his message, if malfunction occurs in the device due to the calling party's voices, ambient noise at the side of the calling party or circuit noise, the device is put in its remote-controlled state to rewind and reproduce the tape as mentioned above. In this case, there is a possibility that the recorded contents are overheard by other persons than the possessor of the device. Further, in a case where the calling party abandons the call for some reasons after sending out a remote control signal for a short time, the recording tape is automatically rewound, as described above, and the device continues to close and hold the communication loop circuit, so that the device cannot respond to a new call in this condition.
Besides, when the remote control signal is stopped, if a mark signal is recorded on the message recording tape and left unerased, the tape stops at the position of the mark signal during a reproducing operation, making it impossible to reproduce the subsequent recorded content.
For a remote-controlled automatic answering telephone device of the system which stably stores the recorded content even if a remote control operation takes place, there has heretofore been employed a method which, upon detection of a mark signal after completion of sending out a message, rewinds the recording tape for a predetermined period of time (about 0.3 to 0.5 sec.) and then drives the recording tape for steady-state running (about 15 to 20 sec.) to erase the mark signal, or a method which employs a mark signal detecting magnetic head at the preceding stage of an erase head for erasing the mark signal and which erases the mark signal by energizing the erase head after the detection of the mark signal. In either case, erasing of the mark signal leaves an erased part on the recording tape and the next calling party's message is recorded after the erased part, so that in a case of listening to the message by a remote control operation, an unnecessary silent part is reproduced and sent out, which gives the calling party not only a sense of uneasiness but also such an impression as if reproducing of the message is finished. Further, the abovesaid methods have the defects of prolonged time for remote listening and inefficient use of the tape.